Everyone wants the 401-427-27-Eglinton interchange fixed. Problem is major reconstruction is needed and not only is that very expensive, it will disrupt traffic flow for a long time on an already bottlenecked interchange.
My proposition is to extend the 401's collectors by either building a pair of giant overpasses or tunnel it below. The overpasses will be a giant eyesore to local residents and with all the support coulombs for the existing structures, tunnels may not be possible. Something needs to be done, but the logistics of the project is what has stalled it.
the 401-403-410 interchange will be completed in the coming years as the 401's collectors are extended west. Weather or not the finished interchange will be fully connected remains to be seen. Loop ramps could be used to connect the missing connections... its too expensive to build new flyovers and there seems to be enough room left behind for this.